Dark material = less reflection?
"Strongly reflecting" and "dark" are mutually exclusive.

However, maybe all you need to do is decrease the saturation of your material's colour. If the colour contains no red or green components, then there will be no red or green components in the reflected colours and the material will look quite dark.

For example, here are three reflective balls rendered in Cycles. From left to right, the saturation of the blue colour applied to these materials is 70%, 85% and 100%. With a lower saturation, the results look a lot more natural.